5 Answers
5

It sounds to me like you are interested in showing some application specific coloring for your Google maps display (rather than traffic maps).

If so , then you should check out custom overlays. You can create your own transparent background overlay tiles (with your colored streets), match them up with the Google maps tiles and then overlay them on the map. You can find a description of this stuff in the Maps API reference - Overlays.

I have actually been interested in trying this out, and this question might be a good excuse. I'll let you know how I go.

Edit: Ok, I tried this and it was pretty straightforward. You just need to grab the tiles images when the google maps page load (for the area you would like to overlay). Make sure you keep track of the origional urls, because these have the x,y coordinates that you will need to write your tile overlay method.

Edit the tiles with your colored roads then upload them to your web server. Add the following code to use your overlay on the regular map:

And if you want to obtain the coordinate (latitude, longitude) of certain streets, you may have a look to the source code of this page

I am not sure to fully understand your question: do you want to mark some given streets ?
in that case, a quick-and-dirty way could be to get the coordinates of all the addresses of the street and build a GPolygon according to them...

Try digging into the code used to show the traffic overlay on the normal Google Maps site.

Edit: I just looked at the code, and it appears that even Google decided it was easier to implement this by just generating the traffic lines on the server and pulling them down as transparent PNG overlays.